Throughout her life, O'Connor maintained a wide correspondence, including with writers Robert Lowell and Elizabeth Bishop, English professor Samuel Ashley Brown, and playwright Maryat Lee. After her death, a selection of her letters, edited by her friend Sally Fitzgerald, was published as The Habit of Being. Much of O'Connor's best-known writing on religion, writing, and the South is contained in these and other letters.
In 1955, Betty Hester, an Atlanta file clerk, wrote O'Connor a letter expressing admiration for her work. Hester's letter drew O'Connor's attention, and they corresponded frequently. For The Habit of Being, Hester provided Fitzgerald with all the letters she received from O'Connor but requested that her identity be kept private; she was identified only as "A." The complete collection of the unedited letters between O'Connor and Hester was unveiled by Emory University in May 2007; the letters were given to the university in 1987 with the stipulation that they not be released to the public for 20 years.